1. Field of the Invention
The present invention relates generally to a standalone solar energy conversion system, and more particularly to a standalone solar energy conversion system with maximum power point tracing and method of operating the same.
2. Description of Prior Art
The solar photovoltaic system provides a photovoltaic conversion to generate a DC power through the solar cell panels. Afterward, the DC power is converted into an AC power through a power conditioner to supply to a load or the converted AC power is grid-connected to an AC utility power through the utility grid bus. The solar photovoltaic system can be broadly divided into three categories: (1) stand-alone system, (2) grid-connection system, and (3) hybrid system.
The stand-alone system means that the solar photovoltaic system is completely operational without requiring external support and only directly supply to a load. Hence, the stand-alone system is generally built in remote areas or isolated islands. In particular, the required power electricity of a load is either the wind power or the solar power. The solar power or/and the wind power can further provide redundant power to charge the standby battery, whereas the load can be supplied through the battery when the solar power or/and the wind power is insufficient. The grid-connection system means that the solar photovoltaic system is further connected to the power grid of the electric power company. Hence, the grid-connection system is suitable for where the utility power can reach. When the amount of electricity generation of the solar photovoltaic system is greater than that of load demands, the redundant power remains would be delivered to the utility grid bus. On the other hand, the utility power can provide the required power electricity to a load when the amount of electricity generation of the solar photovoltaic system is insufficient. Furthermore, in order to improve the power supply reliability and quality, the hybrid system is developed. The solar photovoltaic system, which is combined with standby batteries, is temporarily separated from the utility power to provide power electricity to a load when the utility power fails. The solar photovoltaic system is further grid-connected to the utility grid bus until the utility power is available.
Intensity of sunlight and operating temperature are two important factors of influencing characteristics of the photovoltaic panel. When the photovoltaic panel is operated in a rapidly changing environment, temperature and illumination are changing all the time. Therefore, external loads must be properly controlled in order to achieve the maximum output power of the photovoltaic panel. Otherwise, the photovoltaic panel maybe cannot provide enough energy to the external loads due to changes in environmental conditions, thus causing voltage collapse and abnormal operations. Hence, a maximum power point tracing (MPPT) technology can be adopted to improve the overall efficiency of the solar generation system.
Accordingly, it is desirable to provide a standalone solar energy conversion system with maximum power point tracing and method of operating the same.